This story I've always felt is surprisingly average for the Fourth Doctor's swansong. Tom Baker was such an iconic Doctor, and yet his last hurrah is nothing too remarkable compared to his previous outings.

Logopolis is a decent story, with a clever concept regarding the titular planet that holds the universe together through mathematical equations. It feeds into Adric's character well as a mathematical genius too, giving him a real purpose within the screenplay to assist the workers of Logopolis with the block transfercomputations. I also like the idea of a TARDIS within a TARDIS, and how the Doctor and Adric become stuck in an infinite loop.

However, the Fourth Doctor is surprisingly ineffective for his last story. It's mainly his companions who do all the work, and even though the climactic scene on the telescope is a fantastic piece of television, I can see Tom Baker's concerns in that the fall from the ladder isn't a very dignified way for his incarnation to leave the show. It doesn't work as a 'hero' moment quite as well as the Tenth Doctor absorbing the radiation in The End Of Time.

Probably the best aspect of this serial is the character work. Tegan gets a great introduction, and the serial takes the time to explore the emotional ramifications of her aunt's passing, as well as Nyssa losing her Dad.

I'm glad that they showed Nyssa coming to terms with the Master taking Tremas's body, and the Master cruelly misleading her into believing he was her Dad. It's something the classic series rarely did very well, and it's refreshing to see Logopolis take more time to show how the characters are affected by what's happened.